This invention relates to a device for use in an electrophotographic copying machine and which carries and illuminates an original sheet on which an original image to be copied is provided.
In various types of conventional electrophotographic copying machines, the size of the original sheets to be copied is limited to A-2 (420mm .times. 594mm) at the largest. It has recently been required in various industrial fields that larger copying machines are to be provided to copy larger sizes of the original sheets, such as the sizes of A-1 (594mm .times. 841mm) and A-0 (841mm .times. 1189mm). However, there have been many difficulties in manufacturing such a larger copying machine having a good copying ability for such larger sizes of the original sheets. One of these difficulties results from the original sheet carrying and illuminating device provided in such a larger copying machine.
For various reasons, it is preferable that such an original sheet carrying and illuminating device is arranged to move the original sheet across an associated optical system for projecting the original image to a photosensitive plate of the copying machine on which a latent image is formed. In such a case, however, it is necessary to stably move the sheet at a predetermined speed, but conventional devices of this kind cannot prevent lateral displacement of the larger original sheet as well as its variation in its longitudinal movement, and also has a difficulty in carrying such a larger sheet closely on a supporting plate.
It is further required that the larger copying machine can be used to make copies from transparent, translucent or opaque original sheets, because such a larger copying machine has to be available for transparent or translucent sheets of design drawings ordinarily used in many factories, as well as opaque sheets. It is often desired to make a copy including information described or printed on the back surface of the transparent or translucent original sheet, such as a tracing paper, as well as including information described on the front surface thereof. However, conventional original sheet carrying and illuminating devices are not suitable for such a purpose.